A 54-year-old male patient, who was a smoker, was admitted to the emergency room with acute chest pain and dyspnea. Investigation was initiated by means of computed tomography angiography of the chest, which showed extensive dissection of the thoracic aorta, beginning in the ascending segment (Stanford type A), associated with intramural hematoma of the pulmonary artery trunk and its main branches. It was more evident on the right, which determines local pulmonary luminal reduction, in addition to a small para-aortic and subaortic mediastinal hematoma. There were no signs of pulmonary thromboembolism, and the evaluation of the parenchyma showed no signs of pulmonary hemorrhage ( Figures 1 and 2 ).

Figure 1

Figure 2

Acute aortic dissection is a life-threatening condition, and mediastinal hematoma dissecting the pulmonary artery sheath is considered a rare complication,^{1 - 3} which can simulate pulmonary thromboembolism and vasculitis.⁴ This generally occurs because, at the level just above the aortic valve, the ascending aorta and the pulmonary artery trunk share a common adventitia, which caudally becomes the visceral pericardium.^{1 , 4 , 5} In most cases, there is a rupture of the middle bed adjacent to the right pulmonary artery, and blood flows from the ascending aorta into the interstitial space that limits the pulmonary arteries (intramural hematoma) ( Figure 3 ), and this can extend into the interlobular septa, or even the alveoli, through the peribronchovascular interstitium.^{1 , 2 , 4} Some isolated cases of pulmonary artery hematoma may be related to patent ductus arteriosus, pulmonary hypertension, or connective tissue disorders.^{6 - 9}

Figure 3